Generally, a quinolone compound has a cyclic amine substituent including a second amino moiety at the 7-position (or an equivalent position thereof) of the quinolone skeleton. Such quinolone compounds are generally synthesized by reacting a cyclic amine compound with a 7-halogenated quinolonecarboxylic acid compound. In order to enhance yield and reaction site specificity, the carboxylic acid moiety of a quinolonecarboxylic acid compound is transformed into a borofluoric acid ester moiety or a boric acid ester moiety, followed by reaction with a cyclic amine compound (see Patent Documents 1 to 3 and Non-Patent Documents 1 to 4).
Furthermore, from an industrial viewpoint, there have been developed methods for producing quinolonecarboxylic acid derivatives at high efficiency; e.g., a production method in which an alkyl borate is employed as an additive (Patent Document 4), and a one-pot method (Patent Document 5).    Patent Document 1: JP-A-1987-252772    Patent Document 2: JP-A-1988-316757    Patent Document 3: JP-A-1991-95177    Patent Document 4: JP-A-1993-294938    Patent Document 5: WO 2005/047260    Non-Patent Document 1: Majid M. Heravi et al., Journal of Chemical Research, 2005, 579.    Non-Patent Document 2: Liu Ming-Liang et al., Chinese Journal of New Drugs, 2004, 13, 12, 1130.    Non-Patent Document 3: Liu Ming-Liang et al., Chinese Journal of Pharmaceuticals, 2004, 35, 3, 129.    Non-Patent Document 4: Liu Ming-Liang et al., Chinese Journal of Pharmaceuticals, 2004, 35, 7, 385.